MrWill said: "I don't understand a 60 day cooling off period, but oh well!!"
I think it's to account for returns.
It's still generous, because returns can be made for up to 60 days after the order, but commissions get paid between 30-60 days after it (i.e. commissions get paid on about July 1 for both a purchase made on May 1 - making the commission 60 days later - as well as one made on May 31 - making the commission about 30 days later).
So theoretically, a return could be made on an item that a commission has already been paid for, and EF doesn't subtract those after the commission is paid. I would expect most returns to happen within 30 days though.